Composition, organic light-emitting device, display device, photoelectric conversion apparatus, electronic apparatus, and moving object including the composition

ABSTRACT

A composition contains an organic compound and an anthracene compound different from the organic compound, the anthracene compound having a hydrogen atom at at least one of positions 9 and 10, in which the concentration of the anthracene compound is 100 ppm or less. Additionally, a long-lived organic light-emitting device includes an organic compound layer containing a reduced concentration of the anthracene compound.

BACKGROUND OF THE INVENTION Field of the Invention

The present disclosure relates to a composition in which theconcentration of a specific compound in an organic compound layer isreduced, an organic light-emitting device including the composition andthus having a long driving lifetime, a display device, a photoelectricconversion apparatus, a lighting device, an electronic apparatus, and amoving object including the organic light-emitting device.

Description of the Related Art

An organic light-emitting device is an element which includes a pair ofelectrodes and an organic compound layer disposed between the pair ofelectrodes. The organic compound is excited by energy obtained by therecombination of a hole and an electron supplied from the electrodes.Light is emitted when the excited energy state returns to the groundstate.

Organic light-emitting devices are applied to various devices andrequired to have improved characteristics. In particular, improvementsin driving lifetimes of organic light-emitting devices enable variousdisadvantages of organic light-emitting devices and devices includingthem to be solved. Organic light-emitting devices include organiccompound layers composed of organic compounds. Organic compounds used inorganic compound layers are industrially extracted from, for example,tar, crude oil, or coal as a raw material by various refining methods.In particular, polycyclic aromatic hydrocarbon compounds are oftenobtained from coal used as a raw material by refining. As a polycyclicaromatic hydrocarbon, anthracene is known.

Japanese Patent Laid-Open No. 2003-282268 (hereinafter, referred to as“PTL 1”) describes compound 1-A having an anthracene skeleton and athiophene skeleton as a light-emitting material. U.S. Patent ApplicationPublication No. 2009/0160326 (hereinafter, referred to as “PTL 2”)describes compound 1-B having an anthracene skeleton as an exemplifiedcompound for a blue-light-emitting material having good color purity.

Organic compounds derived from coal contain highly active substances, insome cases. Highly active compounds affect the driving lifetimes oforganic light-emitting devices to decrease the driving lifetime.Hitherto, however, it has not been recognized that such a highly activecompound is contained. No attempt has been made to improve the drivinglifetime of a device by reducing the highly active compound.

PTL 1 and 2 describe highly active compounds such as anthracenecompounds, but do not describe the improvement in the lifetimes ofdevices by reducing the highly active compounds.

SUMMARY OF THE INVENTION

The present disclosure has been made in light of the foregoingdisadvantages. The present disclosure provides a composition having areduced concentration of a highly active compound.

One aspect of the present disclosure is directed to providing acomposition containing an organic compound and an anthracene compounddifferent from the organic compound, the anthracene compound having ahydrogen atom at at least one of positions 9 and 10, the concentrationof the anthracene compound being 100 ppm or less.

Further features of the present disclosure will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating an example of adisplay device including organic light-emitting devices according to anembodiment of the present disclosure and transistors electricallycoupled to the organic light-emitting devices.

FIG. 2 is a schematic view illustrating an example of a display deviceaccording to an embodiment of the present disclosure.

FIG. 3A is a schematic view illustrating an example of an image pickupapparatus according to an embodiment of the present disclosure, and FIG.3B is a schematic view illustrating an example of a portable apparatusaccording to an embodiment of the present disclosure.

FIG. 4A is a schematic view illustrating an example of a display deviceaccording to an embodiment of the present disclosure, and FIG. 4B is aschematic view illustrating an example of a foldable display device.

FIG. 5A is a schematic view illustrating an example of a lighting deviceaccording to an embodiment of the present disclosure, and FIG. 5B is aschematic view illustrating an automobile as an example of a movingobject according to an embodiment of the present disclosure.

DESCRIPTION OF THE EMBODIMENTS

The present disclosure will be described in detail below.

[1] Anthracene Compound Contained in Composition According to Embodimentof Present Disclosure

A composition according to an embodiment of the present disclosurecontains an organic compound and an anthracene compound different fromthe organic compound, the anthracene compound having a hydrogen atom atat least one of positions 9 and 10. When the term “anthracene compound”is simply described in this specification, it refers to an anthracenecompound having a hydrogen atom at at least one of positions 9 and 10.

In the composition according to an embodiment of the present disclosure,the concentration of the anthracene compound is preferably 100 ppm orless, more preferably 50 ppm or less, even more preferably 10 ppm orless.

The anthracene compound may be distinguished by a substituent in theanthracene compound. Specific examples thereof include anthracenecompounds to which chalcogen atoms are bonded, anthracene compoundsconsisting only of hydrocarbons, and anthracene compounds having hydroxygroups. When a chalcogen atom or hydroxy group is bonded to theanthracene skeleton, the chalcogen atom or hydroxy group may be directlybonded to the anthracene skeleton or may be bonded to the anothersubstituent bonded to the anthracene skeleton. The concentration of theanthracene compound in which the chalcogen atom is directly bonded tothe anthracene skeleton can be reduced.

In the case where multiple types of the anthracene compounds arecontained, each of the multiple types of the anthracene compounds may becontained in an amount of 100 ppm or less or 50 ppm or less, preferably20 ppm or less, more preferably 10 ppm or less. In the case where themultiple types of the anthracene compounds are contained, the totalconcentration of the multiple types of the anthracene compounds may be100 ppm or less or 75 ppm or less, preferably 30 ppm or less, morepreferably 25 ppm or less.

In the case where more than three types of the anthracene compounds arecontained, the concentration of each of any two types of the anthracenecompounds can be 20 ppm or less, and the two types of the anthracenecompounds can include an anthracene compound in which a chalcogen atomis bonded to its anthracene skeleton.

The concentration of the anthracene compound can be lower and can beequal to or lower than the detection limit thereof. When the anthracenecompound is contained in an amount of the detection limit, a smallamount of the anthracene compound may be contained. Specifically, theanthracene compound may be contained in an amount of 1 ppm or more, 0.5ppm or more, or 0.1 ppm or more.

The anthracene compound has a hydrogen atom at at least one of positions9 and 10. The anthracene compound is highly active at positions 9 and10. The fact that the anthracene compound has a hydrogen atom at each ofthe positions, i.e., the anthracene compound is unsubstituted at thepositions, indicates that the anthracene compound reacts easily withanother compound. When the anthracene compound reacts with anothercompound, the another compound loses its function. Thus, for example,the driving lifetime of an organic light-emitting device can beshortened.

By reducing the amount of the highly active anthracene compound in thecomposition to enable organic compounds in the composition to be stablypresent, the stability of the composition is improved. The stablecomposition can be present for a long time without losing its function.The use of the stable composition for an organic light-emitting deviceenables the driving lifetime thereof to be improved.

The composition according to an embodiment of the present disclosurecontains an organic compound and an anthracene compound represented byformula [1]. The anthracene compound represented by formula [1] is acompound considered to be contained in the composition together with theorganic compound extracted from coal and so forth. However, the presentdisclosure is not limited to those extracted from coal and so forth aslong as the concentration of the anthracene compound in the compositionis reduced.

In formula [1], R₁ to R₉ are each independently selected from a hydrogenatom, a chalcogen atom, a substituted or unsubstituted alkyl group, asubstituted or unsubstituted aryl group, and a substituted orunsubstituted heterocyclic group. R₁ to R₉ may be the same or different.At least one of R₁ to R₉ is a substituted or unsubstituted aryl group.Adjacent substituents may form a ring. When at least one of R₁ to R₉ isa chalcogen atom, adjacent substituents may be bonded to the samechalcogen atom to form a ring. In other words, adjacent substituentsamong R₁ to R₉ may form a ring via a chalcogen atom.

Examples of the chalcogen atom in formula [1] include atoms of oxygen,sulfur, and selenium.

In formula [1], the alkyl group may be an alkyl group having 1 to 10carbon atoms. Specific examples thereof include a methyl group, an ethylgroup, a n-propyl group, a n-butyl group, a n-pentyl group, a n-hexylgroup, a n-heptyl group, a n-octyl group, a n-decyl group, an isopropylgroup, an isobutyl group, a sec-butyl group, a tert-butyl group, anisopentyl group, a neopentyl group, a tert-octyl group, a cyclopropylgroup, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, acyclopentylmethyl group, a cyclohexylmethyl group, a cyclohexylethylgroup, a 4-fluorocyclohexyl group, a norbornyl group, and an adamantylgroup. The alkyl group may contain a substituent and may contain ahalogen atom. When a halogen atom is contained, the halogen atom can bea fluorine atom. Specific examples thereof include a fluoromethyl group,a difluoromethyl group, a trifluoromethyl group, a 2-fluoroethyl group,a 2,2,2-trifluoroethyl group, a perfluoroethyl group, a 3-fluoropropylgroup, a perfluoropropyl group, a 4-fluorobutyl group, a perfluorobutylgroup, a 5-fluoropentyl group, and a 6-fluorohexyl group.

In formula [1], the aryl group may be an aryl group having 6 to 24carbon atoms. Non-limiting specific examples thereof include a phenylgroup, a naphthyl group, an indenyl group, a biphenyl group, a terphenylgroup, a fluorenyl group, an anthryl group, a phenanthryl group, apyrenyl group, a tetracenyl group, a pentacenyl group, a triphenylgroup, and a perylenyl group.

In formula [1], the heterocyclic group may be a heterocyclic grouphaving 3 to 21 carbon atoms. Examples of a heteroatom include atoms ofoxygen, nitrogen, and sulfur. Non-limiting specific examples thereofinclude a thienyl group, a pyrrolyl group, a pyridyl group, a pyrazylgroup, a pyrimidyl group, a pyridazinyl group, a quinolinyl group, aisoquinolinyl group, an oxazolyl group, an oxadiazolyl group, aphenanthridinyl group, an acridinyl group, a naphthyridinyl group, aquinoxalinyl group, a quinazolinyl group, a cinnolinyl group, aphthalazinyl group, a phenanthrolinyl group, a phenazinyl group, adibenzofuranyl group, a dibenzothiophenyl group, a carbazolyl group, abenzofuranyl group, a benzothiophenyl group, an indolyl group, acycloazyl group, a benzimidazolyl group, a benzothiazolyl group, and abenzothiadiazolyl group.

In formula [1], examples of a substituent attached to the substituents,i.e., the alkyl group, the aryl group, and the heterocyclic group,include alkyl groups having 1 to 6 carbon atoms such as a methyl group,an ethyl group, a propyl group, and a butyl group; aralkyl groups suchas a benzyl group; aryl groups having 6 to 12 carbon atoms such as aphenyl group and a biphenyl group; heterocyclic groups having 3 to 9carbon atoms such as a pyridyl group, a pyrrolyl group, a benzimidazolylgroup, and a benzothiazolyl group; amino groups such as a dimethylaminogroup, a diethylamino group, a dibenzylamino group, a diphenylaminogroup, and a ditolylamino group; alkoxy groups such as a methoxy group,an ethoxy group, a propoxy group, and a phenoxy group; a cyano group;and halogen atoms such as fluorine atoms. Examples of heteroatoms in theheterocyclic group include atoms of oxygen, nitrogen, and sulfur.

Positions 9 and 10 of the anthracene skeleton are easily subjected tohalogenation and oxidation because of their high chemical reactionactivity. Thus, various substituents can be easily provided at positions9 and 10 by subjecting the anthracene skeleton to halogenation and thena coupling reaction with various boronic acids in the presence of ametal catalyst. The substituents provided can be stably present.

However, in an anthracene compound in which hydrogen atoms are presentat both of the 9- and 10-positions, the hydrogen atoms located at thesepositions are easily eliminated to generate radicals. The positionswhere the hydrogen atoms have been eliminated are easily oxidized orreacted with another compound. In other words, the anthracene compoundin which hydrogen atoms are located at both positions 9 and 10 is in anunstable state.

In the case where a hydrogen atom is located at either position 9 orposition 10 of an anthracene skeleton, in other words, in the case wherea substituent is located at one of the positions, the effect of theelectron-donating properties of the substituent further increases thereaction activity at position 9 or 10 where the hydrogen atom islocated. Thus, the anthracene compound is unstable as described above.

Thus, in the case where a hydrogen atom is located at at least one ofpositions 9 and 10 of the anthracene skeleton, the compound is unstable.

The use of the anthracene compound represented by formula [1] does notmerely destabilize the composition. In the case where the anthracenecompound represented by formula [1] is mixed in the organic layer,particularly in the light-emitting layer, of an organic light-emittingdevice, the anthracene compound acts as an exciton quencher to cause adecrease in luminance during continuous current driving. Furthermore,the anthracene compound acts as a charge trap for electrons or holes,and breaks the carrier balance in the light-emitting layer duringcontinuous current driving to generate excess electrons or holes. Theexcessive electrons or holes eventually act as exciton quenchers tocause a decrease in luminance.

The anthracene compound represented by formula [1] is contained inorganic compounds refined from coal, crude oil, or tar. As the organiccompounds, for example, polycyclic aromatic hydrocarbons such as ananthracene compound represented by formula [2] are known. An impuritycontained in a process for synthesizing such a polycyclic aromatichydrocarbon is the anthracene compound represented by formula [1]. Inthe case where the relative purity thereof in the organic compound layerof an organic light-emitting device is measured by high-performanceliquid chromatography and found to be 0.01% or less, i.e., 100 ppm orless, the driving lifetime of the organic light-emitting device can besignificantly improved.

Examples of the polycyclic aromatic hydrocarbon include compoundsrepresented by formulae [2] to [6]. The compounds represented byformulae [2] to [6] are examples of the polycyclic aromatic hydrocarbon,and embodiments of the present disclosure are not limited thereto.

The compounds represented by formulae [2] to [6] are examples of thepolycyclic aromatic hydrocarbon. In the course of refining orextraction, the polycyclic aromatic hydrocarbon can contain ananthracene compound having a hydrogen atom at at least one of positions9 and 10. The polycyclic aromatic hydrocarbon is obtained from a rawmaterial such as tar, crude oil, or coal and thus can contain, as animpurity, an anthracene compound having a hydrogen atom at at least oneof positions 9 and 10.

The compound represented by formula [2] is an example of the polycyclicaromatic hydrocarbon and is an anthracene compound having a substituentother than a hydrogen atom at each of positions 9 and 10.

In formula [2], R₁ to R₁₀ are substituents each independently selectedfrom a hydrogen atom, a substituted or unsubstituted alkyl group, asubstituted or unsubstituted aryl group, and a substituted orunsubstituted heterocyclic group, and may be the same or different,provided that at least one of R₁ to R₉ is a substituted or unsubstitutedaryl group and that neither R₅ nor R₁₀ is a hydrogen atom.

The anthracene compound represented by formula [1] is contained also inpolycyclic aromatic hydrocarbon compounds represented by formulae [3] to[6]. This is because pyrene, chrysene, phenanthrene, and triphenylene,which are basic skeletons of compounds represented by formulae [3] to[6], are polycyclic aromatic hydrocarbons extracted by variouslyrefining a raw material such as tar, crude oil, or coal, similarly toanthracene.

In formula [3], R₁₁ to R₁₉ are substituents each independently selectedfrom a hydrogen atom, a substituted or unsubstituted alkyl group, asubstituted or unsubstituted aryl group, and a substituted orunsubstituted heterocyclic group, and may be the same or different. Atleast one of R₁₁ to R₁₉ may be a substituted or unsubstituted arylgroup.

In formula [4], R₂₀ to R₃₁ are substituents each independently selectedfrom a hydrogen atom, a substituted or unsubstituted alkyl group, asubstituted or unsubstituted aryl group, and a substituted orunsubstituted heterocyclic group, and may be the same or different. Atleast one of R₂₀ to R₃₁ may be a substituted or unsubstituted arylgroup.

In formula [5], R₃₂ to R₄₁ are substituents each independently selectedfrom a hydrogen atom, a substituted or unsubstituted alkyl group, asubstituted or unsubstituted aryl group, and a substituted orunsubstituted heterocyclic group, and may be the same or different. Atleast one of R₃₂ to R₄₁ may be a substituted or unsubstituted arylgroup.

In formula [6], R₄₂ to R₅₃ are substituents each independently selectedfrom a hydrogen atom, a substituted or unsubstituted alkyl group, asubstituted or unsubstituted aryl group, and a substituted orunsubstituted heterocyclic group, and may be the same or different. Atleast one of R₄₂ to R₅₃ may be a substituted or unsubstituted arylgroup.

A composition according to an embodiment of the present disclosure cancontain a polycyclic aromatic hydrocarbon represented by one of formulae[2] to [6] and the anthracene compound represented by formula [1], inwhich the composition can contain 100 ppm or less of the anthracenecompound represented by formula [1]. At an anthracene compound contentof 100 ppm or less, the stability of the composition can be improved tosignificantly improve the driving lifetime of an organic light-emittingdevice including the composition.

The anthracene compound represented by formula [1] often contains achalcogen atom bonded thereto. This is because tar, crude oil, or coal,which is used as a raw material when a polycyclic aromatic hydrocarbonis industrially refined, contains chalcogen atoms. Such a chalcogen atomin the raw material is not removed in an extraction step or refinementstep and is bonded to a final product, in some cases. The chalcogen atommay be a sulfur atom.

In an anthracene compound which is represented by formula [1] and towhich a chalcogen atom is bonded, the reaction activity at positions 9and 10 is further increased by the electron-donating properties of thechalcogen atom. In the case where at least one of positions 9 and 10 isa hydrogen atom, the anthracene compound has high reactivity and thus isunstable, as described above. In particular, in the case where a sulfuratom is bonded as a chalcogen atom, high reactivity is exhibited.Accordingly, in the case where the anthracene compound represented byformula [1] contains a sulfur atom, the anthracene compound is highlyeffective in reducing the anthracene concentration to 100 ppm or less.

[2] Method for Reducing Anthracene Compound Represented by Formula [1]

The anthracene compound represented by formula [1] is referred to as an“impurity”, in some cases. This is because the anthracene compound isunintentionally formed during refining to degrade the performance of atarget object. In the past, for example, halogen atoms have beenrecognized as impurities, and the impurities have been reduced by, forexample, sublimation purification.

The sublimation purification is a method for separating compounds usingdifferent sublimation temperatures of compounds. Sublimation temperatureis affected by the molecular weight of a compound. Thus, compoundshaving similar molecular weights tend to have close sublimationtemperatures. It is difficult to separate an anthracene compound havinga hydrogen atom at at least one of positions 9 and 10 from an organiccompound having a sublimation temperature close to the anthracenecompound, in some cases. In particular, in the case where the organiccompound is a polycyclic aromatic hydrocarbon, it is difficult toseparate the anthracene compound by sublimation purification becausethese compounds have close sublimation temperatures. In particular, inthe case where the impurity and a target organic compound are differentin the bonding of a chalcogen atom, it is difficult to separate thembecause of a small difference in molecular weight therebetween.

To reduce the concentration of the anthracene compound represented byformula [1], the anthracene compound can be separated at a stage wherethe molecular weight is low. In the case of a low molecular weight, theproportion of the impurity is high even at a small difference inmolecular weight, thus increasing the proportion of the impurity. Forexample, industrial purification can be performed at the stage of alow-molecular-weight raw material such as unsubstituted pyrene or ahalogenated pyrene.

It is possible to employ a method for selectively reducing or removingthe anthracene compound represented by formula [1] by subjecting theanthracene compound represented by formula [1] to a chemical reaction.

An example of the method is the Diels-Alder reaction using theanthracene compound represented by formula [1] as a conjugated diene. Inthis case, the anthracene compound represented by formula [1] can have ahydrogen atom at each of positions 9 and 10. For example, maleicanhydride can be used as a dienophile. In the case where the anthracenecompound has a hydrogen atom at each of positions 9 and 10, when maleicanhydride is used as a dienophile, maleic anhydride is selectively addedto positions 9 and 10 of the anthracene compound. An adduct formed bythe reaction differs in polarity from the anthracene represented byformula [1]. Thus, the anthracene compound can be separated from atarget organic compound having a polycyclic aromatic hydrocarbon as abasic skeleton by adsorption treatment such as column purification.

Another example of the method is reaction with peroxide. The reaction ofthe anthracene compound represented by formula [1] with a peroxidechanges the polarity of the anthracene compound. Thus, the anthracenecompound can be separated by, for example, the column purification.Specifically, the case where a sulfur atom is bonded as a chalcogen atomto the anthracene skeleton will be described below. The sulfur atombonded to the anthracene skeleton is selectively oxidized into sulfoxideby reaction with peroxide. In contrast, a polycyclic aromatichydrocarbon that does not contain a sulfur atom does not react withperoxide, so that the polarity of the polycyclic aromatic hydrocarbondoes not change. Owing to a difference in polarity between theanthracene compound represented by formula [1] and a target organiccompound, the anthracene compound can be separated by adsorptiontreatment such as column purification in the same way as above.

The anthracene compound represented by formula [1] can be selectivelyreacted and separated from a composition containing a compound having apolycyclic aromatic hydrocarbon as a basic skeleton through the use ofthese reactions to reduce the concentration of the anthracene compoundrepresented by formula [1].

[3] Organic Light-Emitting Device According to Embodiment of PresentDisclosure

An organic light-emitting device according to an embodiment may includea first electrode, a second electrode, and an organic compound layerdisposed between the first electrode and the second electrode. The firstelectrode and the second electrode may be an anode and a cathode, whichare a pair of electrodes. In the organic light-emitting device accordingto the embodiment, the organic compound layer may be formed of a singlelayer or a stack of multiple layers as long as a light-emitting layer isincluded.

In the case where the organic compound layer is formed of the stack ofmultiple layers, the organic compound layer may include, for example, ahole injection layer, a hole transport layer, an electron-blockinglayer, a hole-exciton-blocking layer, an electron transport layer, andan electron injection layer, in addition to the light-emitting layer.The light-emitting layer may be formed of a single layer or a stack ofmultiple layers. In the case where the organic compound layer is formedof stack of multiple layers, the organic compound layer may include,from the anode side, the hole injection layer, the hole transport layer,the electron-blocking layer, the light-emitting layer, the hole-blockinglayer, the electron transport layer, and the electron injection layer.

The LUMO level of the electron-blocking layer can be higher than that ofthe light-emitting layer. This is because the transfer of electrons fromthe light-emitting layer toward the anode side is reduced. The HOMOlevel of the hole-blocking layer can be lower than that of thelight-emitting layer. This is because the transfer of holes from thelight-emitting layer toward the cathode side is reduced.

Here, the HOMO refers to the highest occupied molecular orbital, and theLUMO refers to the lowest unoccupied molecular orbital. A high HOMOlevel and a high LUMO level indicate a state closer to the vacuum level.A high HOMO level is also referred to as a shallow HOMO level. The sameapplies to the LUMO.

The organic compound layer of the organic light-emitting deviceaccording to the embodiment preferably contains 10 ppm or less, morepreferably 5 ppm or less, even more preferably 1 ppm or less of ananthracene compound having a hydrogen atom at at least one of positions9 and 10. In Examples of this specification, the measurement limit isless than 5 ppm; however, measurement can be performed by anothermethod.

The organic compound layer including multiple layers stacked may bedisposed between the first electrode and the second electrode. Only theorganic compound layer may be disposed between the first electrode andthe second electrode. The organic compound layer may be in contact withthe first electrode and the second electrode. In this case, the organiccompound layer may contain 5 ppm or less of the anthracene compound.

The concentration of the anthracene compound in the hole transport layercan be lower than the concentration of the anthracene compound in thelight-emitting layer.

The concentration of the anthracene compound in the electron transportlayer can be lower than the concentration of the anthracene compound inthe light-emitting layer.

In the organic light-emitting device according to the embodiment, atleast one layer in the organic compound layer contains a compositionaccording to the embodiment. Specifically, the composition according tothe embodiment is contained in any of, for example, the hole injectionlayer, the hole transport layer, the electron-blocking layer, thelight-emitting layer, the hole-exciton-blocking layer, the electrontransport layer, and the electron injection layer. The compositionaccording to an embodiment of the present disclosure can be contained inthe light-emitting layer.

In the organic light-emitting device according to the embodiment, in thecase where the composition according to the embodiment is contained inthe light-emitting layer, the light-emitting layer may be a layerconsisting only of the composition according to the embodiment or may bea layer composed of the composition according to the embodiment andanother compound.

The light-emitting layer may contain a host serving as a first compoundand may contain a guest serving as a second compound. The light-emittinglayer may include, from the anode side, a first light-emitting layer anda second light-emitting layer. The second light-emitting layer may be incontact with the cathode side of the first light-emitting layer. Thefirst light-emitting layer may include a first host, a first guest, anda second guest. The second light-emitting layer may include a secondhost and a third guest. The first host and the second host may be anidentical compound.

Here, the host refers to a compound having the highest proportion, byweight, of compounds constituting the light-emitting layer. The guestrefers to a compound that has a lower proportion, by weight, than thehost in the compounds constituting the light-emitting layer and that isresponsible for main light emission. The guest is also referred to as adopant, in some cases. An assist material refers to a compound that hasa lower proportion, by weight, than the host in the compoundsconstituting the light-emitting layer and that assists the lightemission of the guest. The assist material is also referred to as asecond host.

The inventors have conducted various studies and have found that in thecase where a composition according to an embodiment of the presentdisclosure is used for the organic compound layer of the organiclight-emitting device, a device that emits light with high efficiency,high luminance, and very high durability can be obtained. The organiccompound layer includes the light-emitting layer. The light-emittinglayer may be formed of a single layer or multiple layers. Onelight-emitting layer may contain light-emitting materials that emitlight beams of different emission colors. The light-emitting device canemit white light by a combination of light beams of multiple emissioncolors. The term “multiple layers” used here refers to a state in whicha light-emitting layer and another light-emitting layer are stacked.Stacking refers to a state in which the organic compound layers arestacked in the direction from one electrode to the other electrode.

The composition according to an embodiment of the present disclosure canbe used as the constituent material of an organic compound layer otherthan the light-emitting layer included in the organic light-emittingdevice according to the embodiment. Specifically, the composition may beused as the constituent material of, for example, the electron transportlayer, the electron injection layer, or the hole-blocking layer. Thecomposition can be used as the constituent material of the hole-blockinglayer adjacent to the light-emitting layer.

The structure of the organic light-emitting device according to theembodiment is not limited thereto. For example, the following variouslayer structures may be used: Insulating layers are disposed atinterfaces between the electrodes and the organic compound layer. Anadhesive layer or an interference layer is disposed. The electrontransport layer or the hole transport layer is formed of two layershaving different ionization potentials.

The light extraction structure of the organic light-emitting device maybe a top emission structure in which light emerges from the electrodeopposite to a substrate, may be a bottom emission structure in whichlight emerges from the substrate, or may be a structure in which lightemerges from both sides. In the case where light emerges from thesubstrate, the substrate and the electrode adjacent to the substrate canbe optically transparent. In the case where light emerges from theopposite side to the substrate, the electrode opposite to the substratecan be optically transparent.

In the organic light-emitting device according to the embodiment, aknown compound may be used together with the composition according tothe embodiment of the present disclosure, as needed. Specific examplesof the known compound include low-molecular-weight andhigh-molecular-weight hole injection compounds and hole transportcompounds, compounds serving as a host, light-emitting compounds,electron injection compounds, and electron transport compounds. Examplesof these compounds will be illustrated below.

As a hole injection-transport material, a material having a high holemobility can be used so as to facilitate the injection of holes from theanode and to transport the injected holes to the light-emitting layer.To reduce a degradation in film quality in the organic light-emittingdevice, such as crystallization, a material having a high glasstransition temperature can be used.

Examples of low-molecular-weight and high-molecular-weight materialshaving hole-injecting and hole-transporting properties includetriarylamine derivatives, aryl carbazole derivatives, phenylenediaminederivatives, stilbene derivatives, phthalocyanine derivatives, porphyrinderivatives, poly(vinyl carbazole), polythiophene, and other conductivepolymers. Furthermore, the hole injection-transport materials areappropriately used also for the electron blocking layer.

Non-limiting specific examples of a compound used as the holeinjection-transport material will be illustrated below.

Among the hole transport materials illustrated above, HT16 to HT18 canbe used for a layer in contact with the anode to reduce the drivingvoltage. HT16 is widely used in organic light-emitting devices. HT2,HT3, HT10, and HT12 may be used for an organic compound layer adjacentto a layer composed of HT16. Multiple materials may be used for oneorganic compound layer. For example, a combination of HT2 and HT4, acombination of HT3 and HT10, or a combination of HT8 and HT9 may beused.

Examples of a light-emitting material mainly associated with alight-emitting function include condensed-ring compounds such asfluorene derivatives, naphthalene derivatives, pyrene derivatives,perylene derivatives, tetracene derivatives, anthracene compounds, andrubrene, quinacridone derivatives, coumarin derivatives, stilbenederivatives, organoaluminum complexes such astris(8-quinolinolato)aluminum, iridium complexes, platinum complexes,rhenium complexes, copper complexes, europium complexes, rutheniumcomplexes, and polymer derivatives such as poly(phenylene vinylene)derivatives, polyfluorene derivatives, and polyphenylene derivatives.The term “derivative” indicates a compound whose skeleton can be foundin its structure. For example, BD3 below can be referred to as afluorene derivative. BD6, BD7, GD4, and RD1 can be referred to asfluoranthene derivatives. GD1, GD2, and GD3 can be referred to asanthracene derivatives. GD5 is an anthracene derivative as well as apyrene derivative. Among these, fluoranthene derivatives, anthracenederivatives, and pyrene derivatives can be used. In the case wheremultiple light-emitting materials are used, all the light-emittingmaterials can be fluoranthene derivatives, anthracene derivatives, orpyrene derivatives.

Non-limiting specific examples of a compound used as a light-emittingmaterial will be illustrated below.

Examples of a host or an assist in the light-emitting layer includecarbazole derivatives, dibenzofuran derivatives, dibenzothiophenederivatives, organoaluminum complexes such astris(8-quinolinolato)aluminum, and organoberyllium complexes.

Compounds used as the host or the assist in the light-emitting layer areappropriately used also for the hole-blocking layer.

Non-limiting specific examples of a compound used as the host in thelight-emitting layer will be illustrated below.

Among these, pyrene derivatives represented by EM1 to 4 can be used. Inparticular, EM1 or EM2 can be used.

The electron transport material can be freely-selected from materialscapable of transporting electrons injected from the cathode to thelight-emitting layer and is selected in consideration of, for example,the balance with the hole mobility of the hole transport material.Examples of a material having electron-transporting properties includeoxadiazole derivatives, oxazole derivatives, pyrazine derivatives,triazole derivatives, triazine derivatives, quinoline derivatives,quinoxaline derivatives, phenanthroline derivatives, organoaluminumcomplexes, and condensed-ring compounds such as fluorene derivatives,naphthalene derivatives, chrysene derivatives, and anthracenederivatives. The electron transport materials are appropriately used forthe hole-blocking layer. Non-limiting specific examples of a compoundused as the electron transport material will be illustrated below.

The electron injection material can be freely-selected from materialscapable of easily injecting electrons from the cathode and is selectedin consideration of, for example, the balance with the hole-injectingproperties. The organic compounds include n-type dopants and reducingdopants. Examples thereof include alkali metal-containing compounds suchas lithium fluoride, lithium complexes such as lithium quinolinolate,benzimidazolidene derivatives, imidazolidene derivatives, fulvalenederivatives, and acridine derivatives.

The organic light-emitting device is provided by disposing the anode,the organic compound layer, and the cathode on the substrate. Aprotective layer, a color filter, and so forth may be disposed on thecathode. In the case of disposing the color filter, a planarizationlayer may be disposed between the protective layer and the color filter.The planarization layer can be composed of, for example, an acrylicresin.

Examples of the substrate include silicon wafers, quartz substrates,glass substrates, resin substrates, and metal substrates. The substratemay include switching devices such as a transistor, a line, and aninsulating layer thereon. As the insulating layer, any material can beused as long as a contact hole can be formed to establish the electricalconnection between the anode and the line and as long as insulation witha non-connected line can be ensured. For example, a resin such aspolyimide, silicon oxide, or silicon nitride can be used.

As the constituent material of the anode, a material having a workfunction as high as possible can be used. Examples of the material thatcan be used include elemental metals such as gold, platinum, silver,copper, nickel, palladium, cobalt, selenium, vanadium, and tungsten,mixtures thereof, alloys of combinations thereof, and metal oxides suchas tin oxide, zinc oxide, indium oxide, indium-tin oxide (ITO), andindium-zinc oxide. Additionally, conductive polymers such aspolyaniline, polypyrrole, and polythiophene may be used.

These electrode materials may be used alone or in combination of two ormore. The anode may be formed of a single layer or multiple layers.

In the case where the anode is used as a reflective electrode, forexample, chromium, aluminum, silver, titanium, tungsten, molybdenum, analloy thereof, or a stack thereof may be used. In the case where theanode is used as a transparent electrode, a transparent conductive oxidelayer composed of, for example, indium-tin oxide (ITO) or indium-zincoxide may be used; however, the anode is not limited thereto. Theelectrode may be formed by photolithography.

As the constituent material of the cathode, a material having a lowerwork function can be used. Examples thereof include elemental metalssuch as alkali metals, e.g., lithium, alkaline-earth metals, e.g.,calcium, aluminum, titanium, manganese, silver, lead, and chromium, andmixtures thereof. Alloys of combinations thereof may also be used. Forexample, magnesium-silver, aluminum-lithium, aluminum-magnesium,silver-copper, and zinc-silver may be used. Metal oxides such asindium-tin oxide (ITO) may also be used. These electrode materials maybe used alone or in combination of two or more. The cathode may have asingle-layer structure or a multilayer structure. In particular, silvercan be used. To reduce the aggregation of silver, a silver alloy can beused. Any alloy ratio may be used as long as the aggregation of silvercan be reduced. For example, 1:1 may be used.

A top emission device may be provided using the cathode formed of aconductive oxide layer composed of, for example, ITO. A bottom emissiondevice may be provided using the cathode formed of a reflectiveelectrode composed of, for example, aluminum (Al). The cathode is notparticularly limited. Any method for forming the cathode may be used.For example, a direct-current or alternating-current sputteringtechnique can be employed because good film coverage is obtained andthus the resistance is easily reduced.

After the formation of the cathode, a protective layer may be disposed.For example, a glass member provided with a moisture absorbent can bebonded to the cathode to reduce the entry of, for example, water intothe organic compound layer to suppress the occurrence of displaydefects. In another embodiment, a passivation film composed of, forexample, silicon nitride may be disposed on the cathode to reduce theentry of, for example, water into the organic compound layer and thecathode. For example, after the formation of the cathode, the substratemay be transported to another chamber without breaking the vacuum, and asilicon nitride film having a thickness of 2 μm may be formed by achemical vapor deposition (CVD) method to provide a protective layer.After the film deposition by the CVD method, a protective layer may beformed by an atomic layer deposition (ALD) method.

A color filter may be provided for each pixel. For example, a colorfilter in accordance with the size of a pixel may be provided on anothersubstrate and bonded to the substrate provided with the organiclight-emitting device. A color filter may be formed by patterning on aprotective film composed of, for example, silicon oxide usingphotolithography.

The organic compound layer (for example, the hole injection layer, thehole transport layer, the electron-blocking layer, the light-emittinglayer, the hole-blocking layer, the electron transport layer, and theelectron injection layer) included in the organic light-emitting deviceaccording to an embodiment of the present disclosure is formed by amethod described below.

For the production of the organic compound layer, a dry process such asa vacuum evaporation method, an ionized evaporation method, sputtering,or plasma may be employed. Alternatively, instead of the dry process, itis also possible to employ a wet process in which a material isdissolved in an appropriate solvent and then a film is formed by a knowncoating method such as spin coating, dipping, a casting method, aLangmuir-Blodgett (LB) technique, or an ink jet method.

In the case where the layer is formed by, for example, the vacuumevaporation method or the solution coating method, crystallization isless likely to occur, and good stability with time is obtained. In thecase of forming a film by the coating method, the film in combinationwith an appropriate binder resin may be formed.

Non-limiting examples of the binder resin include poly(vinyl carbazole)resins, polycarbonate resins, polyester resins, acrylonitrile butadienestyrene (ABS) resins, acrylic resins, polyimide resins, phenolic resins,epoxy resins, silicone resins, and urea resins.

These binder resins may be used alone as a homopolymer or a copolymer orin combination as a mixture. Furthermore, additives such as a knownplasticizer, antioxidant, and ultraviolet absorber may be used, asneeded.

Application of Organic Light-Emitting Device According to the Embodiment

The organic light-emitting device according to the embodiment can beused as a component member of a display device or a lighting device.Other applications include exposure light sources forelectrophotographic image forming apparatuses, backlights for liquidcrystal displays, and light-emitting devices including white lightsources and color filters.

The display device may be an image information-processing device havingan image input unit that receives image information from an area orlinear CCD sensor, a memory card, or any other source, aninformation-processing unit that processes the input information, and adisplay unit that displays the input image.

The display unit of an image pickup apparatus or an inkjet printer mayhave a touch-screen feature. The driving mode of the touch-screenfeature may be, but is not limited to, an infrared mode, anelectrostatic capacitive mode, a resistive film mode, or anelectromagnetic inductive mode. The display device may also be used fora display unit of a multifunction printer.

The following describes a display device according to the embodimentwith reference to the attached drawings. FIG. 1 is a schematiccross-sectional view illustrating an example of a display deviceincluding organic light-emitting devices and thin-film transistor (TFT)devices coupled to the organic light-emitting devices. The TFT devicesare an example of active devices.

A display device 10 in FIG. 1 includes a substrate 11 composed of, forexample, glass and an insulating layer 12 thereon, the insulating layer12 being configured to protect the TFT devices or organic compoundlayers. The display device 10 includes the TFT devices 18 on theinsulating layer 12. Each of the TFT devices includes a gate electrode13, a gate insulating film 14 that covers the gate electrode 13, asemiconductor layer 15 that covers the gate insulating film, a drainelectrode 16 in contact with the semiconductor layer 15, and a sourceelectrode 17 in contact with the semiconductor layer 15 and differentfrom the drain electrode 16. An insulating film 19 is disposed on theTFT devices 18. An anode 21 included in each organic light-emittingdevice 26 is coupled to the source electrode 17 through a contact hole20.

The way of electric coupling between the electrodes (the anode and thecathode) included in the organic light-emitting device 26 and theelectrodes (the source electrode and the drain electrode) included inthe corresponding TFT device is not limited to the configurationillustrated in FIG. 1. It is sufficient that one of the anode and thecathode is electrically coupled to one of the source electrode and thedrain electrode of the TFT device.

Although an organic compound layer 22 in the display device 10 in FIG. 1is illustrated as a single layer; however, the organic compound layer 22may be formed of multiple layers. A first protective layer 24 and asecond protective layer 25 are disposed on a cathode 23 in order toreduce the deterioration of the organic light-emitting device.

In the display device 10 illustrated in FIG. 1, the transistors are usedas switching elements; however, metal-insulator-metal (MIM) elements maybe used as switching elements instead.

The transistors used in the display device 10 illustrated in FIG. 1 arenot limited to transistors on a single-crystal silicon wafer and may bethin-film transistors having an active layer on the insulating surfaceof the substrate. Examples of the material of the active layer includesingle-crystal silicon, non-single-crystal silicon materials such asamorphous silicon and microcrystalline silicon, and non-single-crystaloxide semiconductors such as indium-zinc oxide and indium-gallium-zincoxide. Thin-film transistors are also referred to as TFT devices.

The transistors in the display device 10 illustrated in FIG. 1 may beformed in the substrate such as a Si substrate. The expression “formedin the substrate” indicates that the transistors are produced byprocessing the substrate such as a Si substrate. In the case where thetransistors are formed in the substrate, the substrate and thetransistors can be deemed to be integrally formed.

In the organic light-emitting device according to the embodiment, theluminance is controlled by the TFT devices, which are an example ofswitching elements; thus, an image can be displayed at respectiveluminance levels by arranging multiple organic light-emitting devices inthe plane. The switching elements according to the embodiment are notlimited to the TFT devices and may be low-temperature polysilicontransistors or active-matrix drivers formed on a substrate such as a Sisubstrate. The expression “on a substrate” can also be said to be “inthe substrate”. Whether transistors are formed in the substrate or TFTdevices are used is selected, depending on the size of a display unit.For example, when the display unit has a size of about 0.5 inches,organic light-emitting devices can be disposed on a Si substrate.

FIG. 2 is a schematic view illustrating an example of a display deviceaccording to the embodiment. A display device 1000 may include a touchscreen 1003, a display panel 1005, a frame 1006, a circuit substrate1007, and a battery 1008 disposed between an upper cover 1001 and alower cover 1009. The touch screen 1003 and the display panel 1005 arecoupled to flexible printed circuits FPCs 1002 and 1004, respectively.The circuit substrate 1007 includes printed transistors. The battery1008 need not be provided unless the display device is a portabledevice. The battery 1008 may be disposed at a different position even ifthe display device is a portable device.

The display device according to the embodiment may be used for a displayunit of an image pickup apparatus including an optical unit includingmultiple lenses and an image pickup device that receives light passingthrough the optical unit. The image pickup apparatus may include adisplay unit that displays information acquired by the image pickupdevice. The display unit may be a display unit exposed to the outside ofthe image pickup apparatus or a display unit disposed in a finder. Theimage pickup apparatus may be a digital camera or a digital camcorder.The image pickup apparatus may translate to a photoelectric conversionapparatus. Examples of an image capturing method employed in thephotoelectric conversion apparatus may include a method for detecting adifference from the previous image and a method of cutting out an imagefrom images always recorded, instead of sequentially capturing images.

FIG. 3A is a schematic view illustrating an example of an image pickupapparatus according to the embodiment. An image pickup apparatus 1100may include a viewfinder 1101, a rear display 1102, an operation unit1103, and a housing 1104. The viewfinder 1101 may include the displaydevice according to the embodiment. In this case, the display device maydisplay environmental information, imaging instructions, and so forth inaddition to an image to be captured. The environmental information mayinclude, for example, the intensity of external light, the direction ofexternal light, the moving speed of a subject, and the possibility thata subject is shielded by a shielding material.

The timing suitable for imaging is only for a short time; thus, theinformation may be displayed as soon as possible. Accordingly, thedisplay device including the organic light-emitting device according toan embodiment of the present disclosure can be used because of its shortresponse time. The display device including the organic light-emittingdevice can be used more suitably than liquid crystal displays for theseunits required to have a high display speed.

The image pickup apparatus 1100 includes an optical unit (notillustrated). The optical unit includes multiple lenses and isconfigured to form an image on an image pickup device in the housing1104. The relative positions of the multiple lenses can be adjusted toadjust the focal point. This operation can also be performedautomatically.

The display device according to the embodiment may include a colorfilter having red, green, and blue pixels. In the color filter, the red,green, and blue pixels may be arranged in a delta arrangement.

The display device according to the embodiment may be used for thedisplay unit of a portable terminal. In that case, the display devicemay have both a display function and an operation function. Examples ofthe portable terminal include mobile phones such as smartphones,tablets, and head-mounted displays.

FIG. 3B is a schematic view illustrating an example of an electronicapparatus according to the embodiment. An electronic apparatus 1200includes a display unit 1201, an operation unit 1202, and a housing1203. The housing 1203 may accommodate a circuit, a printed circuitboard including the circuit, a battery, and a communication unit. Theoperation unit 1202 may be a button or a touch-screen-type reactiveunit. The operation unit may be a biometric recognition unit thatrecognizes a fingerprint to release the lock or the like. An electronicapparatus having a communication unit can also be referred to as acommunication apparatus.

FIG. 4A is a schematic view illustrating an example of the displaydevice according to the embodiment. FIG. 4A illustrates a display devicesuch as a television monitor or a PC monitor. A display device 1300includes a frame 1301 and a display unit 1302. The light-emitting deviceaccording to the embodiment may be used for the display unit 1302.

A base 1303 that supports the frame 1301 and the display unit 1302 isprovided. The base 1303 is not limited to the structure illustrated inFIG. 4A. The lower side of the frame 1301 may also serve as a base.

The frame 1301 and the display unit 1302 may be curved. These may have aradius of curvature of 5,000 mm or more and 6,000 mm or less.

FIG. 4B is a schematic view illustrating another example of a displaydevice according to the embodiment. A display device 1310 illustrated inFIG. 4B can be folded and is what is called a foldable display device.The display device 1310 includes a first display portion 1311, a seconddisplay portion 1312, a housing 1313, and an inflection point 1314. Thefirst display portion 1311 and the second display portion 1312 mayinclude the light-emitting device according to the embodiment. The firstdisplay portion 1311 and the second display portion 1312 may be asingle, seamless display device. The first display portion 1311 and thesecond display portion 1312 can be divided from each other at theinflection point. The first display portion 1311 and the second displayportion 1312 may display different images. Alternatively, a single imagemay be displayed in the first and second display portions.

FIG. 5A is a schematic view illustrating an example of a lighting deviceaccording to the embodiment. A lighting device 1400 may include ahousing 1401, a light source 1402, a circuit board 1403, an optical film1404, and a light diffusion unit 1405. The light source may include theorganic light-emitting device according to the embodiment. The opticalfilter may be a filter that improves the color rendering properties ofthe light source. The light diffusion unit can effectively diffuse lightfrom the light source to deliver the light to a wide range when used forillumination and so forth. The optical filter and the light diffusionunit may be disposed at the outgoing light side of the lighting device.A cover may be disposed at the outermost portion, as needed.

The lighting device is, for example, a device that lights a room. Thelighting device may emit light of white, neutral white, or any colorfrom blue to red. A light control circuit that controls the light may beprovided. The lighting device may include the organic light-emittingdevice according to the embodiment of the present disclosure and a powersupply circuit coupled thereto. The power supply circuit is a circuitthat converts an AC voltage into a DC voltage. The color temperature ofwhite is 4,200 K, and the color temperature of neutral white is 5,000 K.The lighting device may include a color filter.

The lighting device according to the embodiment may include a heatdissipation unit. The heat dissipation unit is configured to releaseheat in the device to the outside of the device and is composed of, forexample, a metal having a high specific heat and liquid silicone.

FIG. 5B is a schematic view illustrating an automobile as an example ofa moving object according to the embodiment. The automobile includes atail lamp, which is an example of lamps. An automobile 1500 includes atail lamp 1501 and may be configured to light the tail lamp when a brakeoperation or the like is performed.

The tail lamp 1501 may include the organic light-emitting deviceaccording to the embodiment. The tail lamp may include a protectivemember that protects the organic light-emitting device. The protectivemember may be composed of any transparent material having high strengthto some extent and can be composed of, for example, polycarbonate. Thepolycarbonate may be mixed with, for example, a furandicarboxylic acidderivative or an acrylonitrile derivative.

The automobile 1500 may include an automobile body 1503 and windows 1502attached thereto. The windows may be transparent displays if the windowsare not used to check the front and back of the automobile. Thetransparent displays may include the organic light-emitting devicesaccording to the embodiment. In this case, the components, such as theelectrodes, of the organic light-emitting devices are formed oftransparent members.

A moving object according to the embodiment may be, for example, a ship,an aircraft, or a drone. The moving object may include a body and a lampattached to the body. The lamp may emit light to indicate the positionof the body. The lamp includes the organic light-emitting deviceaccording to the embodiment.

As described above, when the device including the organic light-emittingdevice according to the embodiment is used, a stable display can beobtained with good image quality even for a long time display.

EXAMPLES

The present disclosure will be described below by examples. The presentdisclosure, however, is not limited thereto. Table 1 presents compoundscontained in compositions according to an embodiment of the presentdisclosure. In Examples, anthracene compounds A to C are expressed asanthracene compounds, and each of the anthracene compounds isrepresented by formula [1] and has a hydrogen atom at at least one ofpositions 9 and 10.

TABLE 1 Organic Anthracene Anthracene Anthracene compound compound Acompound B compound C Compo- sition 1

Compo- sition 2

Compo- sition 3

Compo- sition 4

Compo- sition 5

Compo- sition 6

Compo- sition 7

The concentration of each of anthracene compounds A to C in eachcomposition of this example is 100 ppm or less. The total concentrationof anthracene compounds A to C is preferably 100 ppm or less, morepreferably 75 ppm or less, even more preferably 30 ppm. Each ofanthracene compounds A to C has a hydrogen atom at at least one ofpositions 9 and 10 and is an example of the anthracene compoundrepresented by formula [1]. Anthracene compound A is an anthracenecompound consisting only of a hydrocarbon. Anthracene compound B is ananthracene compound having a chalcogen atom. Anthracene compound C is ananthracene compound having a hydroxy group. Anthracene compounds A to Care also referred to as impurities A to C.

Each of the naphthyl groups in compositions 1, 3, 5, and 7 in Table 1may be attached at position 2. Each of the anthracene skeletons incomposition 2 may further have a substituent at a position other thanpositions 9 or 10. Each of the biphenyl groups in composition 4 may be9,9-dimethylfluorene. The phenanthryl group in composition 6 may furtherhave a substituent.

Identification of Anthracene Compounds A to C Contained in EachComposition

Each of the compositions described in Table 1 contains the organiccompound and anthracene compounds A to C represented by structuralformulae. Anthracene compounds A to C were identified by analysis with ahigh-performance liquid chromatograph with a tandem mass spectrometer(LC/MS/MS).

The high-performance liquid chromatograph with a tandem massspectrometer is an instrument in which a high-performance liquidchromatograph is directly connected to a tandem mass spectrometer thatcan perform MS/MS measurement. A mass-mass (MS/MS) method is a mode ofmass spectrometry in which structural analysis of a sample can be easilyperformed by measuring fragments, obtained using a first analysissystem, using a second analysis system to detect fragments havingsmaller molecular weights. In Examples, the high-performance liquidchromatograph coupled to a tandem mass spectrometer was used as ananalyzer. As the high-performance liquid chromatograph, Agilent 1100available from Agilent Technologies, Inc. was used. As a massspectrometer, LTQ Orbitrap XL available from Thermofisher scientific wasused.

The concentration of each of anthracene compounds A to C was measured byhigh-performance liquid chromatography, and the relative purity wascalculated.

A measurement sample was provided by preparing a solution of 1 mg of asample in 5 mL chloroform. Measurement was performed under conditions:absorption detector: 254 nm, emission detector: excitation wavelength:354 nm, emission wavelength: 416 nm.

The relative purity of each of anthracene compounds A to C contained incompositions of Examples was determined by this method and found to be0.01% or less=100 ppm or less.

Detection of Anthracene Compound A to C Contained in OrganicLight-Emitting Device

When anthracene compounds A to C are directly detected from the organiccompound layer of the organic light-emitting device, unlike detectionfrom the compositions, anthracene compounds A to C are contained in verysmall amounts and thus cannot be detected by high-performance liquidchromatography, in some cases. In such a case, an analysis method withhigher sensitivity than the measurement method described above can beemployed. There is an analysis method using a time-of-flight massspectrometer (TOF-MS) as a measurement method suitable for this case.The concentration of each of anthracene compounds A to C contained inthe compositions of Examples was determined by this method and found tobe 10 ppm or less with respect to the organic compound contained in theorganic light-emitting device.

Example 1

In this example, organic light-emitting devices having a structurepresented in Table 2 were produced, each of the organic light-emittingdevices having a bottom emission structure in which an anode, a holetransport layer, an electron-blocking layer, a light-emitting layer, ahole-blocking layer, an electron transport layer, an electron injectionlayer, and a cathode were sequentially formed on a substrate.

ITO films were formed on glass substrates and subjected to desiredpatterning to form ITO electrodes (anodes). Here, the thickness of eachITO electrode was 100 nm. Each substrate on which the ITO electrode hadbeen formed in this way was used as an ITO substrate in the followingsteps. Next, resistance heating vacuum evaporation was performed in avacuum chamber at a pressure of 1.33×10⁻⁴ Pa to continuously form anorganic compound layer and electrode layers presented in the followingtable on the ITO substrate. Here, the opposing electrode (metalelectrode layer, cathode) had an electrode area of 3 mm². It is writtenthat composition 1-1 was used as a host; however, the organic compoundin composition 1 is intended to function as the host. That is,anthracene compounds A to C in the composition need not have thefunction of the host.

TABLE 2 Film thickness Material (nm) Anode ITO 100 Hole transport layerHT1 20 Electron-blocking layer HT8 10 Light-emitting layer host:composition 1-1 30 guest: BD6 composition: BD6 = 98:2 (ratio by weight)Hole-blocking layer ET22 10 Electron transport layer ET2 30 Electroninjection layer LiF 1 Cathode Al 100

The characteristics of the resulting devices were measured andevaluated. Each of the light-emitting devices had a maximum emissionwavelength of 450 nm and emitted blue light whose chromaticitycoordinates (X, Y)=(0.14, 0.18).

The composition 1-1 in the light-emitting layer is composition 1, whichis described in Table 1, having a composition ratio described in Table3. A, B, and C in the table indicate anthracene compound A, anthracenecompound B, and anthracene compound C, respectively. The compositionratios in the table are given in units of ppm. Table 3 presents thecomposition ratios of the compositions and the evaluation results ofdurability of the organic light-emitting devices containing thecompositions. Composition 1-2 in the table is composition 1 differentfrom composition 1-1 only in the composition ratio. The same applies tocomposition 1-3. The expression “N.D.” in the table indicates that theconcentration of the compound is less than the measurement limit. Themeasurement limit value in this example is less than 5 ppm. Theexpression “N.D.” in other examples has the same meaning.

Table 3 presents the evaluation results of durability of the organiclight-emitting devices produced in this example. The durability of eachdevice was evaluated by a luminance half-life when the device wascontinuously driven while the current density was maintained at 100mA/cm². A device having a luminance half-life of 1,000 hours or more isdescribed as “AAA”. A device having a luminance half-life of less than1,000 hours and 500 hours or more is described as “AA”. A device havinga luminance half-life of less than 500 hours and 200 hours or more isdescribed as “A”. A device having a luminance half-life of less than 200hours and 50 hours or more is described as “B”. A device having aluminance half-life of less than 50 hours is described as “C”.

TABLE 3 Concentration of Durability anthracene evaluation compound A toC in result of composition 1 (ppm) device Composition A B C at 100mA/cm² Example 1 1-1  20  70 N.D. A 1-2  10  10 N.D. AAA Comparative 1-2150 120 N.D. C example 1

Examples 2 to 5

Organic light-emitting devices were produced in the same manner as inExample 1, except that compositions presented in Table 4 wereappropriately used as the hosts. The characteristics of the resultingdevices were measured and evaluated in the same manner as in Example 1.Table 4 presents the measurement results. As in Example 1, composition3-2 is a composition different from composition 3-1 only in thecomposition ratio.

TABLE 4 Concentration of Durability anthracene evaluation compound A toC in result of composition (ppm) device Composition A B C at 100 mA/cm²Example 2 3-1 N.D.  80 N.D. A Comparative 3-2 N.D. 250 N.D. C example 2Example 3 5-1  20  50 N.D. A Comparative 5-2 500 200 N.D. C example 3Example 4 6-1 N.D.  20  50 AA Comparative 6-2 N.D. 170 450 C example 4Example 5 7-1  20  50  20 A Comparative 7-2 120 200 150 C example 5

Examples 6 and 7

In these examples, organic light-emitting devices having a structurepresented in Table 5 were produced, each of the organic light-emittingdevices having a top emission structure in which an anode, a holeinjection layer, a hole transport layer, an electron-blocking layer, afirst light-emitting layer, a second light-emitting layer, hole-blockinglayer, an electron transport layer, an electron injection layer, and acathode were sequentially formed on a substrate.

Laminated films of Al and Ti having a thickness of 40 nm were formed onglass substrate by a sputtering method and patterned usingphotolithography to form anodes. Here, the opposing electrode (metalelectrode layer, cathode) had an electrode area of 3 mm². Each cleanedsubstrate including the electrode and materials were placed in a vacuumevaporation apparatus. After the apparatus was evacuated to a pressureof 1.33×10⁻⁴ Pa (1×10⁻⁶ Torr), UV/ozone cleaning was performed. Thelayers were formed in such a manner that a layer structure presented inTable 5 was achieved. Sealing was performed in a nitrogen atmosphere.

TABLE 5 Film thickness Material (nm) Hole injection layer HT16 5 Holetransport layer HT2 20 Electron-blocking HT7 10 layer Firstlight-emitting host: composition 10 layer described in Table 6 guest:BD7 (composition: BD7 = 99.5:0.5 (ratio by weight)) Second light- host:composition 10 emitting layer described in Table 6 guest 1: RD1 guest 2:GD4 (composition:RD1:GD4 = 97.7:0.3:2 (ratio by weight)) Hole-blockinglayer ET23 80 Electron transport ET3 30 layer Electron injection LiF 1layer Cathode Mg:Ag = 50:50 10 (ratio by weight)

The characteristics of the resulting devices were measured andevaluated. Each device emitted white light whose chromaticitycoordinates (X, Y)=(0.31, 0.33). Table 6 presents the evaluation resultsof durability of the organic light-emitting devices produced in theseexamples. The durability of each device was evaluated by a luminancehalf-life when the device was continuously driven while the currentdensity was maintained at 100 mA/cm². A device having a luminancehalf-life of 2,000 hours or more is described as “AAA”. A device havinga luminance half-life of less than 2,000 hours and 1,500 hours or moreis described as “AA”. A device having a luminance half-life of less than1,500 hours and 1,000 hours or more is described as “A”. A device havinga luminance half-life of less than 1,000 hours and 500 hours or more isdescribed as “B”. A device having a luminance half-life of less than 500hours is described as “C”.

TABLE 6 Concentration of Durability anthracene evaluation compound A toC in result of composition (ppm) device Composition A B C at 100 mA/cm²Example 6 2-1  10  50  20 A 2-2  10  20  20 AA Comparative 2-3 150 350120 C example 6 Example 7 4-1 N.D.  70 N.D. A 4-2 N.D.  20 N.D. AAAComparative 4-3 N.D. 170 N.D. C example 7

Examples 8 and 9

Organic light-emitting devices were produced in the same manner as inExample 6, except that compositions presented in Table 7 wereappropriately used as materials of the hole-blocking layers.

TABLE 7 Film thickness Material (nm) Hole injection layer HT16 5 Holetransport layer HT2 20 Electron-blocking layer HT7 10 Firstlight-emitting layer host: composition 2-1 10 guest: BD7 (composition2-1: BD7 = 99.5:0.5 (ratio by weight)) Second light-emitting host:composition 2-1 10 layer guest 1: RD1 guest 2: GD4 (composition2-1:RD1:GD4 = 97.7:0.3:2 (ratio by weight)) Hole-blocking layercomposition described in 80 Table 8 Electron transport layer ET3 30Electron injection layer LiF 1 Cathode Mg:Ag = 50:50 10 (ratio byweight)

The characteristics of the resulting devices were measured and evaluatedin the same manner as in Example 6. Table 8 presents the measurementresults. The notation of the evaluation results of durability of thedevices in Table 8 is the same as used in Tables 3 and 6.

TABLE 8 Composition Concentration of Durability anthracene evaluationcompound A to C in result of composition (ppm) device A B C at 100mA/cm² Example 8 1-1  20  70 N.D. A Comparative 1-3 150 120 N.D. Bexample 8 Example 9 5-1  20  50 N.D. A Comparative 5-2 500 200 N.D. Bexample 9

The foregoing assessment results indicate that when the compositioncontaining reduced concentrations of the highly active anthracenecompounds represented by formula [1] is used for the light-emittinglayer and the hole-blocking layer adjacent to the light-emitting layer,the driving lifetime of the organic light-emitting device can beimproved. In particular, the reduction of anthracene compound B issignificantly effective in improving the driving lifetime of the organiclight-emitting device.

Methods for reducing anthracene compounds A to C will be specificallydescribed below.

Example 10

Compounds, a reagent, and a solvent described below were placed into a300-mL round bottomed flask.

Composition 1-3 (A: 150 ppm, B: 120 ppm, C: N.D.): 2 g (4.0 mmol)Maleic anhydride: 0.78 g (8.0 mmol)Dehydrated xylene: 200 mL

Note that A, B, and C in composition 1-3 are anthracene compounds A, B,and C, respectively.

The reaction solution was heated to 145° C. under a stream of nitrogenand stirred for 3 hours under reflux. After the completion of thereaction, the mixture was cooled to room temperature and filtered togive a crude filtered product. The resulting filtered product, areagent, and a solvent described below were placed in a 300-mL roundbottomed flask, and then post treatment and purification were performed.

Alumina: 20 g Chlorobenzene: 150 mL

The mixture was heated and stirred at 80° C. for 1 hour and thenhot-filtered at this temperature. The resulting filtrate wasconcentrated to about 60 mL and then heated to 110° C. to dissolve crudecrystals. Recrystallization was performed by slowly cooling the solutionto room temperature and then 10° C. or lower. The resulting crystalswere filtered. The crystals were subjected to slurry washing with two20-mL portions of toluene at room temperature. The resulting crystalswere subjected to drying and sublimation purification to give 1.4 g(yield: 70%) of composition 1-1. Composition 1-1 was measured byhigh-performance liquid chromatography. The calculation of the relativepurities of anthracene compounds A and B with respect to9,10-di(naphthalen-1-yl)-2-phenylanthracene indicated that theconcentration of anthracene compounds A and the concentration ofanthracene compound B were reduced to 20 ppm and 70 ppm, respectively.

In addition to the foregoing reaction, composition 1-1 thus obtained wassubjected to sublimation purification to give 1.1 g (yield: 75%) ofcomposition 1-2. The calculation of the relative purities of A and B byhigh-performance liquid chromatography in the same manner as aboveindicated that in composition 1-2, the concentration of each ofanthracene compounds A and B was further reduced to 10 ppm.

Compositions 5-2, 6-2, 7-2, 2-3, and 4-1 were similarly treated by themethod described in Example 10 to provide compositions 5-1, 6-1, 7-1,2-1, and 4-2.

Comparative Example 10

First, 1 g (2 mmol) of Composition 1-3 (A: 150 ppm, B: 120 ppm, C: N.D.)was subject to only sublimation purification to give 0.8 g (yield: 80%)of the composition 1-3. The calculation of the relative purities of Aand B to 9,10-di(naphthalen-1-yl)-2-phenylanthracene by high-performanceliquid chromatography in the same manner as above indicated. No changewas seen between the concentration of the relative purities of A and Bafter sublimation purification and the concentration of the relativepurities of A and B before sublimation purification.

Example 11

Compounds, a reagent, and a solvent described below were placed into a500-mL round bottomed flask.

Composition 3-2 (A: N.D., B: 250 ppm, C: N.D.): 2 g (4.4 mmol)mCPBA: 0.23 g (1.3 mmol)

Chlorobenzene: 200 mL

The reaction solution was heated to 50° C. under a stream of nitrogenand stirred for 3 hours. After the completion of the reaction, themixture was cooled to room temperature and filtered to give a crudefiltered product.

The resulting filtered product, a reagent, and a solvent described belowwere placed in a 300-mL round bottomed flask, and then post treatmentand purification were performed.

Alumina: 20 g Chlorobenzene: 300 mL

The mixture was heated and stirred at 60° C. for 1 hour and thenhot-filtered at this temperature. The resulting filtrate wasconcentrated to about 60 mL and then heated to 110° C. to dissolve crudecrystals. Recrystallization was performed by slowly cooling the solutionto room temperature and then 10° C. or lower. The resulting crystalswere filtered. The crystals were subjected to slurry washing with two20-mL portions of toluene at room temperature. The resulting crystalswere subjected to drying and sublimation purification to give 1.2 g(yield: 60%) of composition 3-1. Composition 3-1 was measured byhigh-performance liquid chromatography. The calculation of the relativepurity of anthracene compound B with respect to1,6-di(naphthalen-1-yl)pyrene indicated that the concentration ofanthracene compound B was reduced to 80 ppm.

Compositions 2-1 and 4-3 were similarly treated by the method describedin Example 11 to provide compositions 2-2 and 4-1.

As described above, the compositions containing reduced concentrationsof highly active anthracene compounds (A to C) represented by formula[1] were obtained by the Diels-Alder reaction, which is a selectiveaddition reaction, or the oxidation reaction with mCPBA, which is aperoxide.

Comparative Example 11

First, 0.5 g (1.1 mmol) of Composition 3-2 (A: N.D., B: 250 ppm, C:N.D.) was subject to only sublimation purification to give 0.35 g(yield: 70%) of the composition 3-2. The calculation of the relativepurities of A and B to 9,10-di(naphthalen-1-yl)-2-phenylanthracene byhigh-performance liquid chromatography in the same manner as aboveindicated. No change was seen between the concentration of the relativepurities of A and B after sublimation purification and the concentrationof the relative purities of A and B before sublimation purification.Other compositions have the same result.

According to the present disclosure, by the use of the compositioncontaining reduced concentrations of the highly active compounds for theorganic light-emitting device, the long-lived, stable organiclight-emitting device can be provided.

While the present disclosure has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application Nos.2018-201986, filed Oct. 26, 2018, and 2019-183349, filed Oct. 3, 2019,which are hereby incorporated by reference herein in their entirety.

What is claimed is:
 1. A composition, comprising: an organic compound;and an anthracene compound having a hydrogen atom at at least one ofpositions 9 and 10, wherein a concentration of the anthracene compoundis 100 ppm or less.
 2. The composition according to claim 1, wherein theconcentration of the anthracene compound is 50 ppm or less.
 3. Thecomposition according to claim 2, wherein the concentration of theanthracene compound is 10 ppm or less.
 4. The composition according toclaim 1, wherein the composition contains multiple types of theanthracene compound, a concentration of each of the multiple types ofthe anthracene compound is 100 ppm or less.
 5. The composition accordingto claim 4, wherein the concentration of each of the multiple types ofthe anthracene compound is 50 ppm or less.
 6. The composition accordingto claim 5, wherein the concentration of each of the multiple types ofthe anthracene compound is 10 ppm or less.
 7. The composition accordingto claim 1, wherein the composition contains multiple types of theanthracene compound, and a total concentration of the multiple types ofthe anthracene compound is 100 ppm or less.
 8. The composition accordingto claim 7, wherein the total concentration of the multiple types of theanthracene compound is 75 ppm or less.
 9. The composition according toclaim 8, wherein the total concentration of the multiple types of theanthracene compound is 25 ppm or less.
 10. The composition according toclaim 1, wherein the composition contains multiple types of theanthracene compound, a concentration of each of any two types of theanthracene compound among the multiple types of the anthracene compoundis 20 ppm or less, and wherein the two types of the anthracene compoundinclude an anthracene compound in which a chalcogen atom is bonded toits anthracene skeleton.
 11. The composition according to claim 1,wherein the anthracene compound is represented by formula [1]:

where in formula [1], R₁ to R₉ are each independently selected from thegroup consisting of a hydrogen atom, a chalcogen atom, a substituted orunsubstituted alkyl group, a substituted or unsubstituted aryl group,and a substituted or unsubstituted heterocyclic group, at least one ofR₁ to R₉ is a substituted or unsubstituted aryl group, and adjacentsubstituents in R₁ to R₉ may be bonded to each other to form a ring. 12.The composition according to claim 1, wherein the organic compound is apolycyclic aromatic hydrocarbon.
 13. The composition according to claim12, wherein the organic compound is represented by any of formulae [2]to [6]:

where in formula [2], R₁ to R₁₀ are substituents each independentlyselected from the group consisting of a hydrogen atom, a substituted orunsubstituted alkyl group, a substituted or unsubstituted aryl group,and a substituted or unsubstituted heterocyclic group, provided that atleast one of R₁ to R₉ is a substituted or unsubstituted aryl group andthat neither R₅ nor R₁₀ is a hydrogen atom,

where in formula [3], R₁₁ to R₁₉ are substituents each independentlyselected from the group consisting of a hydrogen atom, a substituted orunsubstituted alkyl group, a substituted or unsubstituted aryl group,and a substituted or unsubstituted heterocyclic group,

where in formula [4], R₂₀ to R₃₁ are substituents each independentlyselected from the group consisting of a hydrogen atom, a substituted orunsubstituted alkyl group, a substituted or unsubstituted aryl group,and a substituted or unsubstituted heterocyclic group,

where in formula [5], R₃₂ to R₄₁ are substituents each independentlyselected from the group consisting of a hydrogen atom, a substituted orunsubstituted alkyl group, a substituted or unsubstituted aryl group,and a substituted or unsubstituted heterocyclic group, provided that atleast one of R₃₂ to R₄₁ is a substituted or unsubstituted aryl group,and

where in formula [6], R₄₂ to R₅₃ are substituents each independentlyselected from the group consisting of a hydrogen atom, a substituted orunsubstituted alkyl group, a substituted or unsubstituted aryl group,and a substituted or unsubstituted heterocyclic group.
 14. Thecomposition according to claim 12, wherein the organic compound is ananthracene derivative having a substituent other than a hydrogen atom ateach of positions 9 and 10 or a pyrene derivative.
 15. The compositionaccording to claim 11, wherein in formula [1], at least one of R₁ to R₉is a chalcogen atom.
 16. The composition according to claim 15, whereinthe chalcogen atom is a sulfur atom.
 17. An organic light-emittingdevice, comprising: an anode; a cathode; and an organic compound layerdisposed between the anode and the cathode, the organic compound layercontaining the composition according to claim
 1. 18. The organiclight-emitting device according to claim 17, wherein the organiccompound layer is a light-emitting layer.
 19. The organic light-emittingdevice according to claim 17, wherein the organic compound layer isformed of a stack of multiple layers.
 20. The organic light-emittingdevice according to claim 19, wherein the multiple layers include, froma side of the anode: a hole injection layer; a hole transport layer; anelectron-blocking layer; a light-emitting layer; a hole-blocking layer;an electron transport layer; and an electron injection layer.
 21. Theorganic light-emitting device according to claim 20, wherein aconcentration of the anthracene compound in the hole transport layer islower than a concentration of the anthracene compound in thelight-emitting layer.
 22. The organic light-emitting device according toclaim 20, wherein a concentration of the anthracene compound in theelectron transport layer is lower than a concentration of the anthracenecompound in the light-emitting layer.
 23. The organic light-emittingdevice according to claim 20, wherein the light-emitting layer includes,from the side of the anode: a first light-emitting layer; and a secondlight-emitting layer in contact with the first light-emitting layer,wherein the first light-emitting layer contains: a first host; a firstguest; and a second guest, and wherein the second light-emitting layercontains: a second host; and a third guest.
 24. The organiclight-emitting device according to claim 23, wherein the first host andthe second host are an identical compound.
 25. A display device,comprising: multiple pixels, at least one of the multiple pixelsincluding: the organic light-emitting device according to claim 17; anda transistor coupled to the organic light-emitting device.
 26. Aphotoelectric conversion apparatus, comprising: an optical unitincluding multiple lenses; an image pickup device that receives lightpassing through the optical unit; and a display unit that displays animage captured by the image pickup device, wherein the display unitincludes the organic light-emitting device according to claim
 17. 27. Anelectronic apparatus, comprising: a display unit including the organiclight-emitting device according to claim 17; a housing provided with thedisplay unit; and a communication unit being disposed in the housing andcommunicating with an outside.
 28. A lighting device, comprising: alight source including the organic light-emitting device according toclaim 17; and a light diffusion unit or an optical film that transmitslight emitted from the light source.
 29. A moving object, comprising: alamp including the organic light-emitting device according to claim 17;and a body provided with the lamp.
 30. An organic light-emitting device,comprising: a first electrode; a second electrode; and an organiccompound layer disposed between the first electrode and the secondelectrode, the organic compound layer being in contact with the firstelectrode and the second electrode, wherein the organic compound layeris formed of a stack of multiple layers, and the organic compound layercontains 5 ppm or less of an anthracene compound having a hydrogen atomat at least one of positions 9 and
 10. 31. A display device, comprising:multiple pixels, at least one of the pixels including: the organiclight-emitting device according to claim 30; and a transistor coupled tothe organic light-emitting device.
 32. A method for producing acomposition, the composition containing an organic compound and ananthracene compound different from the organic compound, the anthracenecompound having a hydrogen atom at at least one of positions 9 and 10,the method comprising a step of: selectively reacting the anthracenecompound by an addition reaction or an oxidation reaction.
 33. Themethod for producing a composition according to claim 32, wherein theaddition reaction or the oxidation reaction is repeated until aconcentration of the anthracene compound is 100 ppm or less.
 34. Themethod for producing a composition according to claim 32, wherein theaddition reaction is a Diels-Alder reaction.
 35. The method forproducing a composition according to claim 32, wherein the oxidationreaction is an oxidation reaction using a peroxide.